Depressaria radiella

Separated from similar Depressaria species by the distinctive pattern of numerous longitudinal black streaks on the forewings that emanate from the central disc area, terminate at the 3/4 fascia, and consistently end before reaching the wing margin while closely following venation lines.

Wingspan 19–27 mm. Forewings with numerous longitudinal black streaks emanating from central area of disc; most streaks terminate at fascia at 3/4 but always finish before the termen, closely following the venation.

Associated with hostplants in the family Apiaceae, particularly in open habitats where Heracleum and Pastinaca species occur. Found across much of Canada and the United States following range expansion from initial introduction point in Ontario.

Native to most of Europe (except Portugal and most of the Balkan Peninsula). Introduced to North America: first documented in Ontario in 1862, subsequently expanded westward over 160+ years to reach the West Coast. Present across much of Canada and the United States. Also introduced to New Zealand, first recorded in January 2004.

Adults on wing from August to May of the following year after overwintering in sheltered places. Univoltine: one generation per year.

Specialist herbivore feeding on reproductive structures (flowers and developing seeds) of Apiaceae. Effectively restricted to two genera: Heracleum and Pastinaca. Specifically documented on Heracleum sphondylium, Pastinaca sativa, Apium nodiflorum (Europe); Pastinaca sativa and Heracleum maximum in North America.

• Pastinaca sativa - primary hostwild and domesticated parsnip; invasive in North America
• Heracleum maximum - hostAmerican cow-parsnip; only native North American host acquired since introduction
• Heracleum sphondylium - hostEuropean species
• Apium nodiflorum - hostEuropean species

Univoltine throughout its range. Larvae feed on flowers and developing seeds enclosed in silk webbing. Pupation occurs in the main stem of the food plant. Adults emerge in August, overwinter in sheltered places, and remain active until May.

Larvae defend feeding territories by enclosing an umbel in silk webbing. Safely metabolizes ingested furocoumarins (furanocoumarins) from host plants. Populations feeding on different host plants show differential metabolism of angular furanocoumarins. In New Zealand, caused up to 75% reduction in seed production in previously uninfested Pastinaca sativa populations.

Herbivore exerting documented selection pressure on host plants. Drives increases in toxic furanocoumarin (sphondin) content in North American wild parsnip populations, indicating coevolutionary interaction. Potential threat to native North American umbellifers, though host range remains narrow.

Agricultural pest of parsnip crops. Biological control potential: in New Zealand, heavy infestations significantly reduce seed production of invasive Pastinaca sativa. Subject of coevolutionary research documenting plant defense evolution.

• Depressaria depressanacongeneric species; distinguished by broader host range across multiple Apiaceae tribes, higher genetic diversity, faster colonization rate, and more recent North American introduction (2008 vs. 1862)
• Agonopterix heraclianahistorically confused with D. radiella; Linnaeus' original description of 'Phalaena heracliana' actually referred to this species, not the parsnip moth

The species has been subject to 200 years of taxonomic confusion. Linnaeus' 1758 description of 'Phalaena (Tortrix) heracliana' was misidentified as this species by early entomologists; the name actually referred to Agonopterix heracliana. The species was long known as D. pastinacella (based on Duponchel 1838) until ICZN recognition of Goeze's 1783 description as the valid earliest name.

• specialist herbivore
• invasive species
• univoltine
• furanocoumarin metabolism
• coevolution
• agricultural pest
• biological control
• taxonomic confusion
• slow range expansion
• superspecialist

• BugGuide
• Wikipedia
• GBIF taxonomy match
• iNaturalist taxon
• NCBI Taxonomy
• Catalogue of Life
• Genetic Structure and Colonization of North America by Depressaria depressana (Fabricius 1775) (Lepidoptera: Depressariidae) over 15 Years; Contrasts with Westward Expansion of Depressaria radiella (Goeze, 1783) over 160 Years
• Degree of dietary specialization on furanocoumarin-containing hostplants in a newly invasive species, Depressaria depressana (Lepidoptera: Depressariidae)